This invention relates to a method for supporting the manufacture of a magnetic disk which is a discrete track recording medium using a disk-shaped glass substrate and having nonmagnetic regions between tracks formed in a magnetic layer and adapted to record information thereon, and further relates to a method of manufacturing such a magnetic disk.
Aluminum substrates have been widely used as substrates for magnetic recording media. However, following the reduction in size and thickness and the increase in recording density of magnetic disks, there has been an increasing demand for glass substrates that are excellent in substrate surface flatness and substrate strength as compared with the aluminum substrates.
In recent years, following the development of information technology such as the spread of broadband communications and the start of digital broadcasting, there has been an increasing necessity for storing and using a large amount of data. Particularly, for magnetic disks such as hard disks excellent in cost performance, a new technique for further increasing the recording density has been required for satisfying a request that the disk is small enough to be mounted even in a portable device such as a portable telephone or a video camera and, simultaneously, is large in capacity.
Conventionally, in order to increase the recording density of a magnetic disk, use has been made of a technique of reducing the width of a magnetic head and narrowing spaces between data tracks where information is to be recorded, thereby achieving an increase in recording density. However, it has become difficult to ignore a magnetic influence and a thermal fluctuation phenomenon between the adjacent tracks.
Under the circumstances, there has recently been proposed a new type medium called a discrete track recording medium (hereinafter abbreviated as a “DTR medium”) in which data tracks are formed so as to be magnetically isolated from each other (see, e.g. “Development of Ultrahigh-Density Hard Disk Magnetic Recording Medium”, [online], TDK Corporation, [searched Dec. 10, 2006], Internet <URL: http://www.business-i.jp/sentan/jusyou/2006/tdk.pdf>).
The DTR medium is intended for improving the signal quality by removing a magnetic material (grooving process) at portions unnecessary for recording by the use of the newest nanotechnologies such as electron-beam lithography and nanoimprint lithography. Further, after the grooving process, grooves are filled with a nonmagnetic material so as to realize the angstrom-level surface flatness required for magnetic disk drives. The DTR medium has drastically increased the recording density of media to open the way to practical use of ultrasmall-sized large-capacity magnetic disks.
Further, there has also been proposed a new type medium called a patterned medium (a medium adapted to record a signal as a dot pattern) which has been developed from the DTR medium by further increasing the recording density (see, e.g. “Development of Ultrahigh-Density Hard Disk Magnetic Recording Medium” referred to above). This is also a recording medium in the form of a magnetic recording medium for use as a hard disk or the like, in which magnetic particles are regularly arranged artificially.
In addition, there are also a DTR medium in which magnetic tracks are magnetically isolated from each other by pressing a stamper with convex portions onto a flat magnetic layer to form groove portions between the magnetic tracks (see, e.g. Japanese Unexamined Patent Application Publication (JP-A) No. 2007-157311) and a DTR medium having a demagnetized layer formed by ion irradiation (see, e.g. Japanese Unexamined Patent Application Publication (JP-A) No. 2007-226862).